Telephone system



Jan. 14, 1930. R. E. coLLls TELEPHONE SYSTEM Filed June 23, 1928 Afro/wnI atvented `an. 1'4, 1,930'

` UNITED sTA'rEs PATENTv OFFICE RAYMOND E. COLLIS, OF EAST ORANGE, NEWJERSEY, ASSIGNOR TO BELL TELEPHONE l LABORATORIES, INCORPORATED, OF NEWYORK, N. Y., A CORPORATION OF NEW' YORK TELEPHONE sYs'rnM Applicationfiled June 23,

rlhis invention relates toy telephone exchange systems and moreparticularly to systems employing revertive control of selections.

Vith the increase in the use of dial telephone systems,-the length ofthe interoflice t charge flows off very rapidly through the controlrelay of the sender operating that relay while the steady current flowmay not build up fast enough to hold the relay operated. The controlrelay would therefore operate, release and reoperate indicating to thesender that one revertive pulse had been received when such was not thecase, resulting in an inaccurate selection.

In accordance with the present invention, means has been provided forabsorbing the initial discharge without operating the control relay ofthe sender, such means comprising a shunt normally closed around saidcontrol relay and momentarilyincluded in theselection control circuitwhen the circuit is closed through thecontrol relay. This isaccomplished by the use of an auxiliary relay to close the controlcircuit for the purpose of making selections. The shunt around thecontrol relay extends over a back contact of this auxiliary relay whilethe control circuit is closed over a front Contact of this relay and thetwo contacts are so adjusted and related that the shunt is opened iatthe back contact long enough after the control circuit is closed at thefront contact to discharge the control circuitv through the shuntinstead of through the relay. t

For a clearer understanding of the invention reference is made tothedrawing which shows portions of a telephone system to` which theinvention is applicable. The drawing includes portions of a sender anddistrict selector such as are disclosed in Patent 1,589,402 granted June22, 1926 to O. H. Kopp and portions of an incoming 1928. Serial N0.287,791.

selector and a iinal selector such as disclosed 1n Patent 1,658,829granted February 14, 1928 to C. .I-I. Berry. Reference may be made tothese patents for complete descriptions of the operation of the system.i'

As set forth in the Kopp patent above referred to, the initiation of acall by a subscriber causes'the extension of thevcalling line to an idledistrict selector and the asso# ciation of an idle sender with thedistrict selector and the line. The subscrberthen operates his dial toset up a registration ofV the wanted line number. The code of the Wantedoffice istranslated and a control circuit known as the fundamentalcircuit is then established between the sender and the y districtselector for the purpose of controlling district brush selections. Atthe time this fundamental circuit isto be established the districtselector sequence switch which controls cams 100 to 103 inclusive hasbeen advanced to Vposition 3 the sender control sequence switch whichcontrols cams 104 to 106 inclusive has been advanced to position '2 andthe sender sequence switch which controls cams 107 to 110 inclusive isstill vin position 1. As soon as the sender control sequence switchreaches position 2 a circuit is closed for relay 111 extending frombattery, through lthe winding of the relay, upper left contact of cam110, upper right contact of cam 106, to ground, Relay 111 operates toestablish the fundamental circuit. This circuit may be traced frombattery, through the left winding of relay 112, lower right contact ofcam 108, upper left contact of cam 102, through the linlr circuitrepresented by brushes 113 vand 114, lower Contact of cam 109, tooneside k0f contact 115 controlled by relay 111 andl one side of thewinding of relay 116. As relay111 operates it first closes contact 117completing the fundamental circuit over contacts 115 'and 117 in shuntof the winding of relay 116, back contact of relay 118, upper con- -tactof cam 107, resistance 119 to ground.

VIt is obvious that under this condition submental circuit extendsthrough the Winding of relay 116 alone to contact 117 and thence toground as traced. Relays 112 and 116 operate inthe fundamental circuit,relay 112 locking over its left front contact and the left contact ofcam 103 to the funda-V ground, over the conductingsegments lofcommutator strip 121, upper right contact of front contact and `windingof' relay 112 to battery, holding relay k112 operated and yreleasingstepping relay 1116. V'The release off relay 116 .at feachfclosure'othis circuit opcrates a pai-r ofy counting relays Vlin they well knownmanner.- lVhen-theregistration 4has been satisfied, relay 118 operates,opening the fundamental circuit, `releasing relays 112 and 116 and'vcausing the advance (if the district f selector sequence switch and 'thesender sequence switch. VW-ien the sender sequence switch `leaves-psition^1 lrela-yl 111 releases, rst reolosing the shunt Aaround the 1winding of relay 1 -16 a-nd then disconnecting it -from the fundamentalcircuit. r'Phe advance of Athe 4sequence'switch also releases thecounting -relays including relay v1-1-8, preparing tor the nextselection. v

The advance of the district selector se- A quence switch one positionaga-in connects relay 112 to the fundament-'al circuit.

.Vhen the sender lsequence switch-has ad-V vanced two -positions relay`1111 is reoperated again connecting relay 111-6 and its Yshunt into thefundamental circuit andA then removing the Yshunt from the relay -toper-init it toiunction. The intermittent circuit for releasingthestepping relay extends from brush 122', commutator strip 123 and `theupper right `contact of cam 103 lduring dis'y trict group selection.V'Follow-ing group V-selecti-on the district selector hunts for anidleoutgoing tru-nk and the district selector adf'vances -to position 10as described in @the Kopp patent.

rlhe circuit showny `does not include an oiiceselector'and thereforeassu-mes thatthe sender control sequence switch is advanced fromposition 2f-to position 7 under the control of the class sequenceswitch, after which the sender sequence vswitch Tis advanced to position5' and a test :made of .the outgoing trunk over the fundamental circuit-which "extends inposition 5 through relaysnot show-n; VIf the incomingselector -is ready for service the trunk test `causes the advance of'the sender sequence switch to position 16. It will be notedthat relay111 is .operated in positions 4 and 6 of the sender control sequenceswitch, in which positions office selections take place, over the lowercontact of cam106.V

With the sender control sequenceswitcli in position 7 and the sendersequence switch in .position-,1.6, relay 11.1 "isLoperated over theupperleft contact "of cam106 and the upper right contact of cam 110.Relay 124 of the incoming select-or is :connected to the vi.' u ndamental .circuit at :the 'timefthe .trunk test is made and is thereforealready connected to y.the circuit when relay 116 is connected into thecircuit. As set forth above in the arrangement .shownfin the Kopp patentwhen the interoihce trunk is of considerable length a charge is :builtup -on .the trunk conductors during the time thatA the fundamental-cir-- cuit :is .open between trunk testand .the yfirst incomingselection, and when the fundamental `circuit is reclosed .thedissipation of this charge ,may .cause the -stepping .relay .to oper-`ate and release before .the steady currentican build .up .suiiicientlyto A'hold v,the stepping relay operated, thus falsely registeringfareverti-ve pulse. In the arrangement of the present invention .theconnection .of :the shunt .controlled -by relay111 into .the circuit in`parallel with -relayll Ipermitssuch a ,discharge to flow harmlesslyover the shunt and ,prevents the .operation of t'he stepping relay until.the Adirect current ronrthe in coming .selector is. suiiicient ltooperate it.

Tahe fundamental .circuit .for incomingbrush selection maybe traced frombattery, throughthe windingfof relay 124, lower lelt contact of 4cam125., upper. left contact. oat' cam 126, tip brush of :the districtselector, upper Vright and @lower left contacts oi' cam 100, link,brushes 113 and 114, uppercontact of cam 105, contacts yofcam 108,winding of relay 116, contact117, back contact .of relay 11:8, upper`contact of .cam V104, resistance 127 link brushes128 and 129,;'upperleftfand lower right contacts of cam 101, ring brush of the districtselector, contacts o cam 130, to ground.- This .fundamental circuitgremains thesame for all of the subsequent selections, namely, incominggroup selection, l final-brush, final tens and final units .selections,since relay 124 controls the -inalselections -as well as the incomingselections. These,selectionsL take..p,lace in positions 8, 10, .12 vand14 of .the sender sequence switch. In passing from selection toselection relay 111 is released, andeach time that thei'undamentalcircuit is reclosed for another se lection they shunt around relay 116is connected intor the circuit to prevent the false operationv of relay116.` The intermittent circuits for incoming brush and incoming groupselections extend overthe incoming selec-tor commutator strips 136 =and131 respectively and contacts .of cam 125. llo-llowing incomingyselections 'the incoming selector sequence switch advances to position8 and the operation of the inal selector completes intermittent circuitsover commutator strips 133 and 132, contacts of cam 134, ring brush ofthe incoming selector, upper right and lower left contacts of cam 135 tothe winding of relay 124 to hold that relay oper ated and release thestepping relay 116. The operation of the incoming selector and the finalselector are set forth in detail in the Berry patent above referred to.

What is claimed is:

1. In a telephone system, a selector switch, a sender, means forestablishing a control circuit bet-Ween said sender and said switch,

a relay in said sender, a shunt normall closed around said relay, meansfor inclu ing said relay in said control circuit, and means for removingsaid shunt `from said relay only after said relay has been included insaid circuit.

2. In a telephone system, a plurality of selector switches, a sender,means for successively establishing control circuits between said senderand said switches, a relay in said sender, a shunt normally closedaround said relay, means for including said relay in said Vcontrolcircuits, and means for removing said shunt from said relay only aftersaid relay has been included in said circuits.

3. In a telephone system, a plurality of selector switches, a sender,means for successively establishing control circuits between said senderand said switches,l a rst relay in said sender, a shunt normally closedaround said first relay, a second relay in said sender, and meanscontrolledby said second relay control circuits, and means forremovingsaid shunt from said relay only after said relay has been included insaid circuits and for restoring said shunt before said relay isdisconnected rom said circuits.

In witness whereof, I hereunto subscribe my name this 21 day of June,1928.

" RAYMOND E. COLLIS.

for simultaneously including said rst relay and said shunt in saidcontrol circuits and for immediately thereafter removing said shunt.

4. In a telephone system, a plurality of selector switches, a sender,means for successively establishing control circuits between said senderand said switches, a relay in said sender, a second relay in saidsender, means controlled by said second relay for including said firstrelay in said control circuits, and means also controlled by said secondrelay for discharging said control circuits comprising a shunt aroundsaid first relay momentarily included in said control circuits.

5. In a telephone system, a plurality of selector switches, a sender,means for successively establishing control circuits between said senderand said switches, a relay in said sender, a second relay in saidsender, means controlled by said second relay for including said firstrelay in said control circuits, and means also controlled by said secondrelay for discharging said control circuits comprising a shunt aroundsaid first relay, included in said control circuits between the closureof a front contact and the

